I don't know how important it is to pin down the date(s) but I recognize Jerry's MARS shirt from the Fall '80 Warfield acoustic/electric shows and I think the mic may be visible in this pic from the same run.

I was asking myself, but did not go back and preview my work before posting. When i uploaded the picture i questioned the file date used for the name of the picture. Sorry for the confusion, but i really do enjoy the pictures it produced.

I had noticed this at Garcia Band gigs back in the early 80's and I thought it simply was a "reversed speaker" and never questioned it. I also question why I never questioned it! Ha! As usual Mike, super freakin' informative.

I thought I remembered from my earlier attended Dead shows that they had vocal wedges hanging down from the PA trusses, pointing at the band members. Since they were still using floor wedges, too, I wonder if that was some sort of effort to replace the side fill monitors you would see on stages back then, kind of get the whole mix across the stage.

yeah, this is not a reversed speaker. the mic was built into that reversed frame. My guess is it is the voicecoil used as the "antenna" to talk back to the mothership with a couple of filters to reduce the high end you would not normally hear with a traditional speaker and /or with a diaphram mic setup.